Radial tunnel syndrome in psoriatic enthesitis: Complication or coincidence?

Radial tunnel syndrome (RTS) is a rare condition resulting from posterior interosseous nerve (a branch of radial nerve) compression, within the radial tunnel. Lateral epicondylitis as a possible aetiology for RTS has been previously described. Here we report a 64-year-old female, with history of scalp psoriasis, who presented with pain over the lateral aspect of the left elbow and proximal forearm for one year, and decreased sensation over the lateral aspect of distal left forearm including the hand for 20 days. Examination revealed enthesitis at left lateral epicondyle, which was confirmed on magnetic resonance imaging. Touch and pain sensations were reduced over the left thumb, index finger, lateral aspect of the hand and distal forearm, and forearm pain was exaggerated with restricted extension of the wrist and third finger. Rheumatoid factor, anti-nuclear and anti-neutrophil cytoplasmic antibody were negative, and nerve conduction study were normal. A diagnosis of RTS as a possible complication of psoriatic enthesitis was suggested, and patient showed good response to non-steroidal anti-inflammatory drugs.